Plot

Framed in the doorway of Poirot's bedroom stood an univited guest, coated from head to foot in dust. The man's gaunt face stared for a moment, then he swayed and fell.
Who was he? Was he suffering from shock or just exhaustion? Above all, what was the significance of the figure four, scribbled over and over again on a sheet of paper?

Contents

1. The Unexpected Guest
2. The Man from the Asylum
3. We Hear More About Li Chang Yen
4. The Importance of a Leg of Mutton
5. Disappearance of Scientists
6. The Woman on the Stairs
7. The Redium Thieves
8. In the House of the Enemy
9. The Yellow Jasmine Mystery
10. We Investigate at Croftlands
11. A Chess Problem
12. The Baited Trap
13. The Mouse Walks In
14. The Peroxide Blonde
15. The Terrible Catastrophe
16. The Dying Chinaman
17. Number Four Wins a Trick
18. In the Felsenlabyrinth

(different version) The Sketch (UK)
1. The Unexpected Guest (The Sketch, Jan.2 1924)
2. The Adventure of the Dartmoor Bungalow (The Sketch, Jan.9 1924)
3. The Lady on the Stairs (The Sketch, Jan.16 1924)
4. The Radium Thieves (The Sketch, Jan.23 1924)
5. In the House of the Enemy (The Sketch, Jan.30 1924)
6. The Yellow Jasmine Mystery (The Sketch, Feb.6 1924)
7. The Chess Problem (The Sketch, Feb.13 1924)
8. The Baited Trap (The Sketch, Feb.20 1924)
9. The Adventure of the Peroxide Blonde (The Sketch, Feb.27 1924)
10. The Terrible Catastrophe (The Sketch, Mar.5 1924)
11. The Dying Chinaman (The Sketch, Mar.12 1924)
12. The Crag in the Dolomites (The Sketch, Mar.19 1924)